ddi_intr_hilevel(9F)					   Kernel Functions for Drivers 				      ddi_intr_hilevel(9F)

NAME

       ddi_intr_hilevel - indicate interrupt handler type

SYNOPSIS

       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int ddi_intr_hilevel(dev_info_t *dip, uint_t inumber);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

PARAMETERS

       dip	       Pointer to dev_info structure.

       inumber	       Interrupt number.

DESCRIPTION

       ddi_intr_hilevel() returns non-zero if the specified interrupt is a "high level" interrupt.

       High  level interrupts must be handled without using system services that manipulate thread or process states, because these interrupts are
       not blocked by the scheduler.

       In addition, high level interrupt handlers must take care to do a minimum of work because they are not preemptable.

       A typical high level interrupt handler would put data into a circular buffer and schedule a soft interrupt  by  calling	 ddi_trigger_soft-
       intr(). The circular buffer could be protected by using a mutex that was properly initialized for the interrupt handler.

       ddi_intr_hilevel() can be used before calling  ddi_add_intr() to decide which type of interrupt handler should be used. Most device drivers
       are designed with the knowledge that the devices they support will always generate low level interrupts, however some devices, for  example
       those  using SBus or VME bus level 6 or 7 interrupts must use this test because on some machines those interrupts are high level (above the
       scheduler level) and on other machines they are not.

RETURN VALUES

       non-zero        indicates a high-level interrupt.

CONTEXT

       These functions can be called from user or interrupt context.

SEE ALSO

       ddi_add_intr(9F), mutex(9F)

       Writing Device Drivers

SunOS 5.10							    7 Jan 1992						      ddi_intr_hilevel(9F)